Author: mjg Date: Mon Nov 9 23:04:30 2020 New Revision: 367536 URL: https://svnweb.freebsd.org/changeset/base/367536
Log: threads: introduce a limit for total number The intent is to replace the current id allocation method and a known upper bound will be useful. Reviewed by: kib (previous version), markj (previous version) Tested by: pho Differential Revision: https://reviews.freebsd.org/D27100 Modified: head/sys/kern/kern_thr.c head/sys/kern/kern_thread.c Modified: head/sys/kern/kern_thr.c ============================================================================== --- head/sys/kern/kern_thr.c Mon Nov 9 23:02:13 2020 (r367535) +++ head/sys/kern/kern_thr.c Mon Nov 9 23:04:30 2020 (r367536) @@ -67,7 +67,7 @@ __FBSDID("$FreeBSD$"); static SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "thread allocation"); -static int max_threads_per_proc = 1500; +int max_threads_per_proc = 1500; SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW, &max_threads_per_proc, 0, "Limit on threads per proc"); Modified: head/sys/kern/kern_thread.c ============================================================================== --- head/sys/kern/kern_thread.c Mon Nov 9 23:02:13 2020 (r367535) +++ head/sys/kern/kern_thread.c Mon Nov 9 23:04:30 2020 (r367536) @@ -59,6 +59,7 @@ __FBSDID("$FreeBSD$"); #ifdef HWPMC_HOOKS #include <sys/pmckern.h> #endif +#include <sys/priv.h> #include <security/audit/audit.h> @@ -142,6 +143,12 @@ static lwpid_t tid_buffer[TID_BUFFER_SIZE]; static int tid_head, tid_tail; static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); +static int maxthread; +SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN, + &maxthread, 0, "Maximum number of threads"); + +static int nthreads; + struct tidhashhead *tidhashtbl; u_long tidhash; struct rwlock tidhash_lock; @@ -154,8 +161,25 @@ EVENTHANDLER_LIST_DEFINE(thread_fini); static lwpid_t tid_alloc(void) { - lwpid_t tid; + static struct timeval lastfail; + static int curfail; + int nthreads_new; + lwpid_t tid; + nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1; + if (nthreads_new >= maxthread - 100) { + if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 || + nthreads_new >= maxthread) { + atomic_subtract_int(&nthreads, 1); + if (ppsratecheck(&lastfail, &curfail, 1)) { + printf("maxthread limit exceeded by uid %u " + "(pid %d); consider increasing kern.maxthread\n", + curthread->td_ucred->cr_ruid, curproc->p_pid); + } + return (-1); + } + } + tid = alloc_unr(tid_unrhdr); if (tid != -1) return (tid); @@ -185,6 +209,7 @@ tid_free(lwpid_t tid) mtx_unlock(&tid_lock); if (tmp_tid != -1) free_unr(tid_unrhdr, tmp_tid); + atomic_subtract_int(&nthreads, 1); } /* @@ -199,8 +224,6 @@ thread_ctor(void *mem, int size, void *arg, int flags) td->td_state = TDS_INACTIVE; td->td_lastcpu = td->td_oncpu = NOCPU; - td->td_tid = tid_alloc(); - /* * Note that td_critnest begins life as 1 because the thread is not * running and is thereby implicitly waiting to be on the receiving @@ -208,7 +231,6 @@ thread_ctor(void *mem, int size, void *arg, int flags) */ td->td_critnest = 1; td->td_lend_user_pri = PRI_MAX; - EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); #ifdef AUDIT audit_thread_alloc(td); #endif @@ -253,9 +275,6 @@ thread_dtor(void *mem, int size, void *arg) osd_thread_exit(td); td_softdep_cleanup(td); MPASS(td->td_su == NULL); - - EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); - tid_free(td->td_tid); } /* @@ -325,6 +344,8 @@ proc_linkup(struct proc *p, struct thread *td) thread_link(td, p); } +extern int max_threads_per_proc; + /* * Initialize global thread allocation resources. */ @@ -333,6 +354,22 @@ threadinit(void) { uint32_t flags; + /* + * Place an upper limit on threads which can be allocated. + * + * Note that other factors may make the de facto limit much lower. + * + * Platform limits are somewhat arbitrary but deemed "more than good + * enough" for the foreseable future. + */ + if (maxthread == 0) { +#ifdef _LP64 + maxthread = MIN(maxproc * max_threads_per_proc, 1000000); +#else + maxthread = MIN(maxproc * max_threads_per_proc, 100000); +#endif + } + mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); /* @@ -415,16 +452,25 @@ struct thread * thread_alloc(int pages) { struct thread *td; + lwpid_t tid; thread_reap(); /* check if any zombies to get */ - td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); + tid = tid_alloc(); + if (tid == -1) { + return (NULL); + } + + td = uma_zalloc(thread_zone, M_WAITOK); KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); if (!vm_thread_new(td, pages)) { uma_zfree(thread_zone, td); + tid_free(tid); return (NULL); } + td->td_tid = tid; cpu_thread_alloc(td); + EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); return (td); } @@ -447,6 +493,7 @@ void thread_free(struct thread *td) { + EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); lock_profile_thread_exit(td); if (td->td_cpuset) cpuset_rel(td->td_cpuset); @@ -455,6 +502,8 @@ thread_free(struct thread *td) if (td->td_kstack != 0) vm_thread_dispose(td); callout_drain(&td->td_slpcallout); + tid_free(td->td_tid); + td->td_tid = -1; uma_zfree(thread_zone, td); } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
